Socio-Economic, Technical and Environmental Indicators for Sustainable Sewage Sludge Management and LEAP Analysis of Emissions Reduction

Abstract

The waste management sector is transitioning from a dirty and undesirable industry towards a green and sustainable future where energy and materials are recycled. Recycling has potential in sewage sludge treatment, where energy and highly valuable nutrients can be recovered through innovative and sustainable sludge management. Although there are many technologies and techniques already used for sewage sludge, the indicators for their sustainability are not developed. In terms of sustainable and innovative sewage sludge treatment, usually, only techno-economic aspects of existing and current technologies are considered. We explore the existing indicators and propose new indicators for sustainable and innovative sewage sludge treatment technologies. The indicators are differentiated into four main categories: technical, social, environmental and economic, where specific indicators are explained, followed by a description of their impact on sustainability. We also consider a case study using the LEAP tool, which considered GHG emissions when utilizing sewage sludge as an energy feedstock to replace existing fossil fuels in the energy mix in several scenarios. The results showed a significant emissions reduction when sludge is used—37.6% and 90.9% in 2030 and 2050, respectively.